I'm not at all familiar with pebble dash but just did some reading and it sounds like you have a problem. Best would have been try hardest to get it off while still green and before it had dried. One article suggest a low pressure steam cleaner, along with leaving and painting over a few bits of tendril - rather than aim for a complete removal that would have you removing many of the pebbles in the process. Are there any professionals within your area (and within your budget) you could call to help you with this?

Maybe you'd have better luck with removing it using a brush and cleaning solution as described in Pebble dash cleaning tips step 3 of instead of trying to remove the dry ivy. Painting the pebble dash doesn't sound like fun because of its rough surface which is presumably why there are commercial coating offerings (All Weather Coating, Corksol).

Thank you very much, I will see if I can get a low pressure cleaner and ifnot possible I will try the cleaning solution although I don't have great hopes as it is very stuck on the wall...It was definitely a bad idea let the green ivy dry! 

Thank you for the tips

This is the affected wall...

I just looked on YouTube, and there are lots of videos on your issue. You may want to look at them. Best of luck!